This website uses cookies

This website uses cookies to give you the best user experience. You have disabled cookies which will render many features of the GSL website unusable. To change your cookie settings, select the option below and follow the instructions. These instructions are also obtainable from the privacy & cookies link at the bottom of any GSL page.

This website uses cookies to give you the best user experience. If you continue without changing your settings we'll assume you are happy to receive all GSL cookies. To change your cookie settings, select the option below and follow the instructions. These instructions are also obtainable from the privacy & cookies link at the bottom of any GSL page.

The Geological Society offers grades of membership for every stage of your career, from student to retirement. Find out about the benefits of membership, and how we can help you achieve and maintain Chartered status.

Information about the Geological Society’s internationally acclaimed books and journals for authors, editors, librarians and readers. Order publications, find out about the Lyell Collection and read guidelines for preparing a paper or submitting a book proposal.

Information and resources for teachers and students from
primary education onwards; for those making careers choices
after A-levels including undergraduate and further degrees
at university; and for those seeking professional
geosciences training or exploring lifelong learning
opportunities.

News and updates for the press, policy makers and members of the public interested in how the geosciences
interact with society. Find updates about policy related meetings, consultation responses, position statements and
press releases.

Geoscientist is the Fellowship magazine of the Geological Society: with news about science, people, the Society, features, reviews, opinion, letters and forthcoming events. All this, and more, can be found sooner here, in our online version.

The Geological Society of London is the UK national society for geoscience, providing support to over 11,500 members in the UK and overseas. Founded in 1807, we are the oldest geological society in the world.

Petroleum Geoscience

The international journal of geoenergy and applied earth science

A co-owned journal of the Geological Society of London and the European Association of Geoscientists and Engineers (EAGE)

Petroleum Geoscience transcends disciplinary boundaries and publishes a balanced mix of articles covering exploration, exploitation, appraisal, development and enhancement of sub-surface hydrocarbon resources and carbon repositories. The integration of disciplines in an applied context, whether for fluid production, carbon storage or related geoenergy applications, is a particular strength of the journal. Articles on enhancing exploration efficiency, lowering technological and environmental risk, and improving hydrocarbon recovery communicate the latest developments in sub-surface geoscience to a wide readership.

Published by both The Geological Society of London and EAGE, Petroleum Geoscience is a peer-reviewed journal providing a multidisciplinary forum for those engaged in the science and technology of the rock-related sub-surface disciplines. The journal reaches some 8000 individual subscribers, and a further 1100 institutional subscriptions provide global access to readers including geologists, geophysicists, petroleum and reservoir engineers, petrophysicists and geochemists in both academia and industry. The journal aims to share knowledge of reservoir geoscience and to reflect the international nature of its development.

Chief editor

Philip Ringrose, Equinor ASA, Norway

Online in the Lyell Collection

The journal is included the Lyell Collection and articles appear online soon after they have been accepted for publication and ahead of the printed volume or issue. From May 2018 journal articles will be posted as accepted manuscripts and then replaced by the published article (the version of record). The journal is easily accessible on mobile devices.

Print journal

Petroleum Geoscience is published in print in February, May, August and November.

The journal is abstracted and/or indexed in:

Current Contents

GeoArchive

Geobase

Geological Abstracts

GeoRef

Mineralogical Abstracts

Petroleum Abstracts

Science Citation Index

Recent Petroleum Geoscience Highlights

Geology and hydrocarbon potential of the East African continental margin: a review

By Ian Davison and Ian Steel

The East African margin has a complex structure due to multiple phases of rifting with different stretching directions. The main phase of rifting leading to Indian Ocean opening lasted from the Late Pliensbachian to the Bajocian (c. 183 – 170 Ma). This occurred during impingement of the Bouvet hotspot which weakened the lithosphere sufficiently to allow continental break-up. Thick salt and marine shales were deposited during the Toarcian in the Majunga, Ambilobe and Mandawa basins and the onshore Ogaden Basin; marking the onset of the Indian Ocean marine incursion, when good quality oil-prone source rocks were deposited at this time. The recent giant gas discoveries in Tanzania and Mozambique are believed to be sourced from overmature Jurassic or, possibly, deeper Permian age Karoo shales. The margin from the Lamu Basin in the north to the Zambesi Delta in the south is covered by thick Tertiary and Cretaceous sediment derived from the East African rift shoulders, and Lower Jurassic source rocks are predicted to be in the gas window along most of the margin. However, the margins in South Africa, south Mozambique, northern Somalia and Madagascar are less deeply buried, and have better oil potential.
The large Tsimimo and Bemolanga tar sand deposits and the recent announcement of an oil rim in the Inhasorro Field indicate that there are good oil-prone source rocks in the Karoo rifts and in the Albian Domo shales; and the search for oil continues with companies exploring in areas where Jurassic source rocks may be less deeply buried, and/or potential Albian–Turonian-aged source rocks are sufficiently buried to generate oil.

Inversion of satellite-derived free-air gravity-anomaly data has been used to map crustal thickness and continental lithosphere thinning in the South China Sea. Using this, we determine the ocean–continent transition zone structure, the distal extent of continental crust, and the distribution of oceanic lithosphere and continental fragments in the South China Sea. We construct a set of regional crustal cross-sections, with Moho depth from gravity inversion, spanning the South China Sea from offshore China and Vietnam to offshore Malaysia, Brunei and the Philippines to examine variations in ocean–continent transition structure and ocean-basin width. Our analysis shows a highly asymmetrical conjugate margin structure. The Palawan margin shows a narrow transition from continental to oceanic crust. In contrast, the conjugate northern margin of the South China Sea shows a wide region of thinned continental crust and an isolated block of continental crust (the Macclesfield Bank) separated from the Chinese margin by a failed oceanic rift. The Dangerous Grounds are predicted to be underlain by fragmented blocks of thinned continental crust. We use maps of crustal thickness and continental lithosphere thinning from gravity inversion together with free-air gravity- and magnetic-anomaly data to identify structural trends and to show that rifting and the early seafloor-spreading axis had an ENE–WSW trend while the later seafloor-spreading axis had a NE–SW trend.

This study uses previously unpublished reflection seismic data and wells to map part of the western margin of the Hormuz salt basin for the first time, and to link Hormuz facies distribution to the evolution of major structures in NE Saudi Arabia. Most of these major structures host giant or supergiant oil fields in Mesozoic reservoirs. This study is based on seismic interpretation of structural style because the Hormuz occurs at up to 10 km or more depth present day and is not penetrated by any wells. In the eastern part of the study area, seismically transparent zones with structural elements diagnostic of salt tectonics pass laterally into layered seismic facies with local clinoform geometries. The transparent facies are interpreted as mobile salt, the layered facies as immobile evaporite basin-margin strata. The layered facies display onlap and fault-bound relationships with older basement domains, and in map view the boundary between layered and transparent seismic facies at the Hormuz level forms embayments and promontories on the west margin of the salt basin. Areas of mobile salt underlie domal and periclinal structures, such as Karan, Hasbah, Dammam and Khursaniyah. These structures display steeply dipping reflections at depth that can be interpreted as salt pillow flanks, with base salt locally interpretable, and have plan-view aspect ratios of 2 or less. Beyond the limits of layered seismic facies, between the embayments and westwards towards the Arabian Shield, seismic and well data indicate that the major structures are not salt cored, including Berri, Manifa, Safaniya, Jauf, Juraybi'at and Haba.